Opposites Attract (It's A Boy Girl Thing)
by themortalsaga
Summary: Clary and Jace have lived across from each other for years. And they hate each other. But what will happen when they somehow end up in each other's bodies? Based on the movie Its A Boy Girl Thing. First fanfic, sorry I suck at summaries.
1. Chapter 1

**Hi! So this is my first ever fanfic, its going to be based on the movie 'Its A Boy Girl Thing'. If I get positive feedback on this chapter, I'll continue the story. So PLEASE PLEASE PLEASE tell me what you think!**

**I do not own The Mortal Instruments characters, because if I did, there would have been some more clace action by now. All rights go to the lovely Cassandra Clare. **

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_"I can't frikkin' believe this."_ Clary inwardly groaned as she stomped down the asphalt pavement. _"First day back and I'm already running late. Fantastic." _The school bus had started driving away just as she came running down the driveway, flailing her arms wildly in an attempt to stop the bus. Needless to say, it didn't work. Clary had watched the bus drive away with a hand against her forehead, the kids sitting in the back shouting "Loser!" and making obscene gestures all the while. _Idiots._

_And on top of being late, I forgot to pick up my coffee flask off the counter. Could this day get any worse?_

The sound of protesting tires and loud music turned the corner behind Clary. She rolled her eyes before throwing a glance over her shoulder. _That was supposed to be a rhetorical question._

"Hey Clare!" a sarcastic voice shouted over the bouncing beat of the music.

Just as Clary turned to shout back a nasty retort, a wave of water sprayed up and completely drenched her. Angry and stunned, Clary wiped the water off her face just in time to see a black haired boy and a boy with hair like a golden halo, smack their hands together in a high five as they drove off down the street.

_Jace Herondale, being a vexatious asshole since 1991. _


	2. Chapter 2

**Hey! Thank you so much for the positive feedback! I'm having so much fun writing this story and its only just begun *evil laughing***

**And here I give you Chapter 2!**

**I unfortunately, do not own the characters from The Mortal Instruments.**

**UPDATE: Changed Clary's last name to Morgenstern because I realised it didn't really make sense for the next chapter.**

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Jace was still laughing when they arrived at school. Clary, who had stood soaking wet with her hands curled into fists at her side, had given Jace a look of pure hatred. Comical, considering her height did nothing to make her look intimidating.

"Man, she's so going to kick your ass." Alec said, grinning as he parked the car in a space in the school's parking lot.

"I'd like to see her try." Jace challenged.

Just as Jace finished his sentence, he spotted Clary walking up the steps to the school entrance, her hair a mass of curls, her jaw locked and her head held high. She turned her head towards him, as if she could feel his gaze burning into the back of her head. Clary glared, leaving a chuckling Jace with the phrase 'If looks could kill' stuck in his mind as he stepped out of the car.

* * *

Clary refused to go home and change. _No, I'm not giving that pretentious ass the satisfaction._

Clary now walked up the marble steps into the front entrance of Idris Academy, her fiery red hair hanging in damp, frizzy curls around her pale freckly face. She kept her head high as she ignored the stares and sniggers of the students around her.

Jace and Clary had lived across the road from one another for as long as she could remember. And they both hated each other for as long as she could remember. They hadn't even had a conversation without them going at each other's throats. This incident was just another to add to the list of How Does Jace like to Ruin Clary's Life.

_This is going to end. Now_

Simon, Clary's best friend, was stood beside her locker with a small smirk on his face.

"Wow, Morgenstern. Forget to use the hair gel this morning?"

Clary rolled her eyes. "Shut it, Lewis. So not in the mood today."

"Let me guess...Jace?"

She nodded, frowning as she looked into the small mirror hanging inside her locker, trying to tame the wild frizz her hair had become.

"You really ought to do something about him." Simon said, his face softening as he looked at her one last time before heading down to his first class.

Clary, slightly happier with the state of her hair than she was five minutes ago, gathered up her books and took one step towards her first class before hearing a deep, boyish laugh behind her.

"Sorry about that puddle this morning, it just came up right in front of us"

Clary spun round to see Jace leaning casually against the row of lockers with a mocking grin on his face. Her hand itched to smack it off.

_Yeah right. _

"Oh look, its special needs boy." Clary replied, doing her best to sound scornful.

Jace opened his mouth to make a sarcastic remark but Clary beat him to it.

"You have fun teasing me and making me look like a joke now but just remember that this is the best your life will get." Clary continued when Jace quirked a brow.

"The whole popular football star thing? That stops the minute you graduate. Then you'll be stuck in a dead end job with that slut Kaelie you call a girlfriend doing sexual favors to bring in enough money for you to survive the week." Clary snapped, a wicked smile playing at the corners of her mouth.

"So have fun while it lasts." She called back over her shoulder as she walked off down the hall.

Jace stood staring after Clary as she walked off, mouth hanging open in astonishment.

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**Review!**


	3. Chapter 3

**Hey again! I'm doing my best to update at least once a day now because school tests etc coming up and I might not be able to update as frequently. Also, I can't wait until they actually switch bodies. **

**Anyway, this chapter just gives a little background on Jace and Clary, and sets things up for later in the story.**

**Enjoy!**

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The red headed girl watched the whole exchange from around the corner. She smiled angelically as she watched Clary strut down the corridor, leaving Jace dumbfounded.

_I can't wait to have a little fun with these two. _

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Clary sat in her room later that night, with her sketchbook in hand drawing quietly. She frowned through her concentration as she tried to redraw a line which just didn't want to look the way she wanted it to.

"Clary, there's mail for you!" Clary's mom, Jocelyn, shouted from the bottom of the staircase. Clary put her sketchbook down, got up from her spot on her bed and walked downstairs. She halted in front of Jocelyn who was standing with an envelope in her hand in the hallway. Clary took the envelope from a grinning Jocelyn who walked back through to the kitchen.

Clary's eyes widened as she read the return address on the letter; New York Institute of Arts.

_My dream university._

She ripped open the envelope and quickly read over the letter. A scream erupted from her as she read the words 'invite you to be interviewed'.

"OH MY GOD, I HAVE AN INTERVIEW AT THE NEW YORK INSTITUTE OF ARTS!" Clary squealed as she ran through to the kitchen to see Jocelyn at the stove and her dad Valentine sitting at the dining table. He looked up from reading his paper and beamed.

"Of course they do, they'd be lucky to have such a talented young woman as a student." He said as Clary hugged him from behind and sat down at the table beside him.

Clary brushed a red curl out of her face in time to see Jocelyn smiling down at her with pride as she came around the kitchen worktops and handed her a plate.

"Congratulations honey."

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Jace sat on one of the recliners in the living room, pigging out on his TV dinner while the television ran on in the background. His parents, Celine and Stephen, were sat in the tattered love seat across the room, also eating their TV dinners.

"So big game in a few weeks, son" Stephen said casually as he tore through a chicken wing.

Jace just nodded as he stuffed some fries into his mouth.

"And there's supposed to be some college scouts there."

A pressure that was starting to become familiar started up in Jace's stomach. He'd spent the last few days worrying about the game and college. Clary's words today had hit a sensitive spot inside him.

"Yeah, I know." He replied in a low tone.

"You'll do great son, don't waste your time worrying about it." Stephen winked as he went back to watching the TV.

Jace gave him a small smile which he didn't see.

_Yeah, I hope so._

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**So I would've added that first bit in in Chapter 2 but I hadn't thought of it until after it was published. Silly me!**

**Yes, Valentine is a good guy in this story. **

**Review! :)**


	4. Chapter 4

**Hey! Thank you so so much for all the great reviews, I'm glad you're enjoying reading this story as much as I enjoy writing it.**

**I know the last few chapters have been short, so I made this one extra long.**

**I think you'll all enjoy it...**

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I walked into school the next Monday in one, dry, piece. I had missed the bus again but Jace and his imbecile friend Alec hadn't been around to take the piss out of me this time. Well, it's only 9am. They still have time.

The first week back at school had ended uneventfully. Apart from the fact that I had to scream at Jace from my bedroom window across the road to turn his goddamn music down because I was trying to study and him repeatedly making a joke out of me when he could, which apparently means writing on my locker door and messing with my computer in Biology. Yeah, uneventful.

I was sitting in the computer lab working on my DNA project while Mr Garroway droned on about how this project was worth 25% of our final grades and how this year, our final year at high school, is the most important of our lives.

I was really getting sick of hearing it from _every single teacher_.

I bent down to grab my notebook out of my bag. That was when the sounds of grunts and moans filtered through someone's speakers. I shook my head.

_Ugh. _I thought. _In the middle of school, seriously? Disgusting._

Then I realised, as I straightened up having found my notebook in my bag among the sea of school books, that the noises were coming through _my _speakers.

I gave one glance at the screen and my jaw hit the floor. I was mortified.

It had opened up at some sleazy porn website.

I narrowed my eyes as I turned to look at Jace, who was sitting beside me. He was doing his best to look innocent but the minute I looked at him he erupted into a fit of laughter, which joined the other giggles from the rest of the students in the lab. I made a disgusted noise as I turned back around and furiously typed on the keyboard, bringing up Google.

A coughing noise came from behind me and I cursed under my breath before spinning round and looking up into the face of a very disgruntled Mr Garroway who was peering at me over the top of his glasses.

"You may want to...um...delete that page from your personal preferences." He muttered as he walked back around the long table of computers.

I looked back at Jace, who was currently running his hands through his mane of golden hair trying to calm himself down.

"You are seriously such a moron." I said angrily as I turned back to face my computer.

Most of the students had already turned back to their computers except Kaelie who sneered at me wickedly from across the aisle. _Bitch._

And another red-headed girl who was sitting directly opposite me. She was never in any of my classes and I had never seen her before. Her irises were such a vivid green that they seemed to consume the whites of her eyes. I looked at her questioningly as she glanced between Jace and me before sending me an innocent smile and turning back to her computer. There was something stirring in her eyes as she smiled that made me think she wasn't all that innocent.

By the end of class, Mr Garroway had announced we'd be going on a trip to the American Museum of Natural History the following week.

And today was that unfortunate day.

I walked down the steps towards my biology teacher who was standing by the bus doors with a checklist and a hand stuck out taking in permission slips. As I walked towards the bus, I spotted Jace, who was leaning in over a very scantily clad Kaelie, sticking his tongue down her throat. Christ, they looked like they were trying to eat each other.

It would've gone further if Mr Garroway hadn't followed my disgusted stare and asked them if they were done yet. They broke apart and Kaelie locked eyes with me as I walked onto the bus.

"What're you looking at, ginge?"

I considered arguing back but figured she wasn't worth it. I gave her the finger before settling myself down at a seat near the back, sticking my earphones in.

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I was now stood in a circle among the other students under a mass of sharks and other sea-life creatures hanging from the ceiling as our museum tour guide gave us an over enthusiastic lecture on biodiversity. I looked up from my note-taking when the tour guide paused mid-sentence to look over at Jace and Alec, who were stood around the sperm whale model, making crude gestures and jokes.

"Boys, I don't think that is...relevant to our topic of discussion." The petite young woman said with a nervous smile.

"If you could please rejoin the group...?"

The boys began walking back over, still laughing and pushing each other playfully. Jace came and stood beside me, putting on a mask of mock seriousness as he pretended to be intrigued with the lecture.

I rolled my eyes.

"And now we are going to let you wonder off around the exhibits yourself..." the woman finished her lecture up "...Mr Garroway, if you wouldn't mind pairing the students up?"

_Oh dear lord please let me be with Simon._

Simon, who was standing on Clary's other side, unfortunately got paired up with Isabelle, a beautiful raven haired girl who was currently dating Alec. And since everyone else was already paired up, that meant...

"Miss Morgenstern, if you could pair up with Mr Herondale please."

_Well this is going to be just great._

"Let's hope I don't lose any brain cells today" I murmured to myself, pinching the bridge of my nose.

"Excuse me, you should be honoured that you're partnered up with me." Jace replied arrogantly, his eyes a molten gold, condescending.

"I really hate you."

"That's because you secretly want to have sex with me."

I couldn't help but laugh coldly at that.

"Please, if we were the only humans left who could reproduce I still wouldn't...do it with you."

"You're such a virgin; you're too scared to even say 'sex'."

"At least I'm not dating the personification of chlamydia."

I folded my arms defensively as he closed his eyes and ran a hand through his hair. I was beginning to piss him off. Good.

"At least I can get a girlfriend, you're so bitter that no one wants to date you."

This was getting nowhere and we were wasting time.

"I'm done talking to you." I sighed as I began walking past him.

"It's about time your big mouth closes." _Ugh._

I was about to turn back around to really give it to him but I spotted the same redheaded girl from last week, Seelie Queen her name was, standing half in-half out the shadow of a pillar. She was watching our heated exchange intently, frowning a little as if trying to concentrate on something else at the same time.

A moment later, I started to feel a strange pressure, tingling in the centre of my chest. I looked back towards Jace who was rubbing at the centre of his chest as if he could also feel it.

I spun around to look back at where Seelie stood but she was gone. The strange pressure lifted in seconds and I let out a sigh as I pushed past Jace purposefully, who shoved past me heading in the opposite direction.

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**Yeah so I took a few lines directly from the movie.**

**The next chapter is when the fun starts...**

**Review :)!**


	5. Chapter 5

**This chapter was so fun to write so I hope you all enjoy it. I forgot to mention last chapter that I'm going to start writing in dual POVs because it makes writing it easier when they switch bodies.**

**Warning: this chapter jumps POVs a bit.**

**Enjoy :D!**

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Jace's POV

I walked back into my room with tissues and began rubbing the stains on the bed. So _that_ phone call with Kaelie had gone a bit far.

A half hour of scrubbing at the bed sheets made no difference and I ended up having to strip the duvet. I shoved the sheets into the hamper before walking to the linen closet in the hall and grabbing a blanket off one of the shelves.

I stripped down and got into bed, thinking of the weird feeling I got in my chest earlier in the museum and how Clary the bitter hag seemed to feel it too. It had to be a coincidence.

And with no further thought on the matter, I chucked my football at the wall which made a thud on the light switch. The room went dark and I fell quickly into a deep, and much needed, sleep.

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Clary's POV

I woke up the next morning feeling lightheaded and a bit sore.

_Must've been a dream._

I yawned and stretched before opening my eyes sleepily. I gasped in shock and did a double take as I looked wearily around the room.

This wasn't my room.

I sprang out of the bed quickly. There were sports posters hung all round the room with the occasional naked woman. Ew.

But it was when I looked into the mirror on the wardrobe door that I screamed.

Jace was staring back at me, mouth gaping, with a mixture of shock and confusion on his face. I tore my gaze away from the mirror and slowly looked down at my body.

I had a sun-kissed tan, a lean build and a defined muscular torso. And my breasts were gone.

_Oh my god my breasts are gone._

I ran my hands over my chest. Very flat.

And as I looked further down my body at the snug black boxers...

_Oh. My. God_.

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Jace's POV

I waved my arm about trying to find the bleeping alarm clock on the bedside table. My muscles felt sore, as if I had football training the night before. But I hadn't.

Frowning, I got up out of the huge purple double bed.

_Wait, why is my bed purple?_

I looked down at myself to see I was wearing green flannel pyjamas. And there were two small lumps protruding from my chest.

_What the fu—_

I ripped off the green flannel top and stared down at my chest.

_Holy shit, I have tits. Two tits. _

_This cannot be normal for a guy._

I felt for the waistband on the pyjama bottoms and pulled it out.

_MY DICK IS GONE._

What was happening?

I ran over to the mirror on the white dressing table to find a pale, freckly, redheaded Clary staring back at me.

I screamed. A high pitched, girlish scream. _Fuck._

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Clary's POV

My eyes widened as I looked down.

_Okay, I'm pretty sure a teenage girl is NOT supposed to have an erection._

I went quickly over to the window which faced straight over to my room across the street. Jace had obviously had the same idea because he, or should I say I, was leaning out the window topless, staring back at me with a very startled expression.

A masculine voice escaped when I said slowly, trying to stay calm. "Jace, get back inside you don't have a shirt on. We need to talk."

Covering my chest with my hands, he narrowed green eyes at me and nodded, red curls escaping the messy bun at the back of his head.

"Yes, we do." He replied in a girlish voice.

I went back into the room and got dressed before racing past Jace's parents who screamed after me that breakfast was on the table.

"I...uh...I'm running late, see you later!" I called back over my shoulder as I ran out the front door.

I jogged across the road and stood beside my fence as I waited on Jace. He walked out a few minutes later, dressed in what was probably the most revealing outfit I have ever worn. I was wearing a pair of very short ripped denim shorts, a black bralet I had decided was way too revealing for wear and a pair of black leather boots. On top of that, he had me in red lipstick that I don't even remember owning. _I look like Kaelie. _

"What the hell am I wearing?"

Jace smiled devilishly.

"I thought I may as well have some fun while I'm in your body."

I smacked my hand against my forehead.

"I look like a freaking whore."

"Well at least you'll garner some male attention." He winked.

I growled, and stunned myself. I had never made a noise like that in my life. _Oh the joys of being stuck in a teenage boy's body._

We started our walk to school in silence. _This is so weird and messed up._

"So what the fuck did you do that got us stuck in each other's bodies, huh?" He looked up at me accusingly.

"You think I did this? Why the hell would I want to be stuck in your body, of all people?" I bit back defensively.

"Maybe because you're infatuated with me."

I gave him a 'get real' look.

"What are we going to do?" he said after some time.

I glanced down at him. _Christ I am small._

"Maybe it's just a twenty-four hour thing, like a cold. We could be back to normal tomorrow. So let's just try and get through the day okay?"

"Fine whatever." He looked around as we arrived at school, as if he didn't want to be seen with me.

_Ass._

"I would say try to not draw any attention to yourself but with the way you have me dressed I think it's a little late for that."

"Oh no. I'm going to have a little fun today." He replied, his tone teasing.

"I swear to god Jace—"

He patted the side of my face and winked before strutting off up the school steps, swaying my hips.

"I'll see ya later, sweet cheeks." He added in a sugar sweet tone over his shoulder as he entered the building.

_This was going to be an interesting day._

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**Again, I took some lines from the movie because those scenes were just hilarious.**

**Review!**


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